nu_command/strings/str_/
starts_with.rs

1use nu_cmd_base::input_handler::{CmdArgument, operate};
2use nu_engine::command_prelude::*;
3
4use nu_utils::IgnoreCaseExt;
5
6struct Arguments {
7    substring: String,
8    cell_paths: Option<Vec<CellPath>>,
9    case_insensitive: bool,
10}
11
12impl CmdArgument for Arguments {
13    fn take_cell_paths(&mut self) -> Option<Vec<CellPath>> {
14        self.cell_paths.take()
15    }
16}
17
18#[derive(Clone)]
19
20pub struct StrStartsWith;
21
22impl Command for StrStartsWith {
23    fn name(&self) -> &str {
24        "str starts-with"
25    }
26
27    fn signature(&self) -> Signature {
28        Signature::build("str starts-with")
29            .input_output_types(vec![
30                (Type::String, Type::Bool),
31                (Type::List(Box::new(Type::String)), Type::List(Box::new(Type::Bool))),
32                (Type::table(), Type::table()),
33                (Type::record(), Type::record()),
34            ])
35            .allow_variants_without_examples(true)
36            .required("string", SyntaxShape::String, "The string to match.")
37            .rest(
38                "rest",
39                SyntaxShape::CellPath,
40                "For a data structure input, check strings at the given cell paths, and replace with result.",
41            )
42            .switch("ignore-case", "search is case insensitive", Some('i'))
43            .category(Category::Strings)
44    }
45
46    fn description(&self) -> &str {
47        "Check if an input starts with a string."
48    }
49
50    fn search_terms(&self) -> Vec<&str> {
51        vec!["prefix", "match", "find", "search"]
52    }
53
54    fn is_const(&self) -> bool {
55        true
56    }
57
58    fn run(
59        &self,
60        engine_state: &EngineState,
61        stack: &mut Stack,
62        call: &Call,
63        input: PipelineData,
64    ) -> Result<PipelineData, ShellError> {
65        let substring: Spanned<String> = call.req(engine_state, stack, 0)?;
66        let cell_paths: Vec<CellPath> = call.rest(engine_state, stack, 1)?;
67        let cell_paths = (!cell_paths.is_empty()).then_some(cell_paths);
68        let args = Arguments {
69            substring: substring.item,
70            cell_paths,
71            case_insensitive: call.has_flag(engine_state, stack, "ignore-case")?,
72        };
73        operate(action, args, input, call.head, engine_state.signals())
74    }
75
76    fn run_const(
77        &self,
78        working_set: &StateWorkingSet,
79        call: &Call,
80        input: PipelineData,
81    ) -> Result<PipelineData, ShellError> {
82        let substring: Spanned<String> = call.req_const(working_set, 0)?;
83        let cell_paths: Vec<CellPath> = call.rest_const(working_set, 1)?;
84        let cell_paths = (!cell_paths.is_empty()).then_some(cell_paths);
85        let args = Arguments {
86            substring: substring.item,
87            cell_paths,
88            case_insensitive: call.has_flag_const(working_set, "ignore-case")?,
89        };
90        operate(
91            action,
92            args,
93            input,
94            call.head,
95            working_set.permanent().signals(),
96        )
97    }
98
99    fn examples(&self) -> Vec<Example<'_>> {
100        vec![
101            Example {
102                description: "Checks if input string starts with 'my'",
103                example: "'my_library.rb' | str starts-with 'my'",
104                result: Some(Value::test_bool(true)),
105            },
106            Example {
107                description: "Checks if input string starts with 'Car'",
108                example: "'Cargo.toml' | str starts-with 'Car'",
109                result: Some(Value::test_bool(true)),
110            },
111            Example {
112                description: "Checks if input string starts with '.toml'",
113                example: "'Cargo.toml' | str starts-with '.toml'",
114                result: Some(Value::test_bool(false)),
115            },
116            Example {
117                description: "Checks if input string starts with 'cargo', case-insensitive",
118                example: "'Cargo.toml' | str starts-with --ignore-case 'cargo'",
119                result: Some(Value::test_bool(true)),
120            },
121        ]
122    }
123}
124
125fn action(
126    input: &Value,
127    Arguments {
128        substring,
129        case_insensitive,
130        ..
131    }: &Arguments,
132    head: Span,
133) -> Value {
134    match input {
135        Value::String { val: s, .. } => {
136            let starts_with = if *case_insensitive {
137                s.to_folded_case().starts_with(&substring.to_folded_case())
138            } else {
139                s.starts_with(substring)
140            };
141            Value::bool(starts_with, head)
142        }
143        Value::Error { .. } => input.clone(),
144        _ => Value::error(
145            ShellError::OnlySupportsThisInputType {
146                exp_input_type: "string".into(),
147                wrong_type: input.get_type().to_string(),
148                dst_span: head,
149                src_span: input.span(),
150            },
151            head,
152        ),
153    }
154}
155
156#[cfg(test)]
157mod tests {
158    use super::*;
159
160    #[test]
161    fn test_examples() {
162        use crate::test_examples;
163
164        test_examples(StrStartsWith {})
165    }
166}
nu_command/strings/str_/starts_with.rs

nu_command/strings/str_/
starts_with.rs
